Summary: 23
Chapter 2. Synthesis of Parallel Kinematic XY Flexure
Mechanisms
2.1 Design Requirements and Challenges
Compact XY flexure stages that allow for large ranges of motion are desirable in several applications
such as semiconductor mask and wafer alignment [54-55], scanning interferometry and atomic force
microscopy [39,48,59], micromanipulation and microassembly [60], single molecule experiments in
physics and biology [61], high-density memory storage [62] and MEMS sensors [63] and actuators [41].
Since most of these applications require nanometer or even sub-nanometer positioning, flexure-based
motion stages are the only bearing choice available [64]. But the limitation of existing XY flexure stages
is their relatively small range of motion. Although magnetic and air bearings may be used to achieve large
range high precision motion [2], these are not ideally suited for nanometric positioning because of their
size. In some cases large range single DOF flexure stages have been designed [35-36], but large range XY
flexure stages are rare in the current technical literature.
There are three relevant length dimensions: size of stage, maximum range of motion, and motion
resolution. In this discussion, the ratio between range of motion and stage size is referred to as the specific
range, and the ratio between the range of motion and the motion resolution is referred to as the dynamic
range. In the applications above, high specific as well as dynamic ranges are desirable. The dynamic
range of a precision milling machine axis [range ~ 0.5m, resolution ~ 5Ám], and a motorized precision
micrometer driven stage [range ~ 10mm, resolution ~ 0.1 Ám] is of the order of 1e-5. While similar